In trying to figure out how to make my improvised shelters more efficient, I came up with an idea that, while not the most convenient or environmentally friendly, certainly seems to hold promise.

I've been using spray foam insulation on things like truck canopies, plastic buckets, molding blanks, and it occurred to me that a 12 oz can of spray foam might be just the ticket for "hardening" my more immobile sheltering needs.

It used to be that I would pack a couple of large plastic garbage bags, some wire ties, and some duct tape with me in order to build a "quansit hut" type e-shelter using branches as the frame to drape and secure the opened bags over. Unfortunately, the bags didn't last long, especially in high winds, and sometimes my shelters ended up being more duct tape than garbage bag. Switching to mylar sheets made a little improvement in the durability and rigidity of the shelter, but the sacrifice was I couldn't make holes in the mylar without it self destructing.

However, if I use the mylar as a molding surface and spray the outside with urethane foam, the resulting structure should be quite rigid, fairly wind and waterproof, and provide insulation against the cold. One 12 oz can should cover the entire shelter (roughly the surface of two 33 gallon opened garbage bags). The foam expands to 120 times it's volume and is tack free in less than two minutes, yet still flexible for maybe 15 minutes or so, depending on conditions. Even if you can't apply it uniformly, it should do a lot for the strucure integrity nonetheless. Another drawback is it would be difficult to apply under less than optimum conditions.

Tell you what, I'll give this a go, take some pics, and let you see how it turns out.

Oh man, I can't wait to see this! Great idea!

Depending on your results I might have to keep a can in the trunk. <img src="/images/graemlins/wink.gif" alt="" />

Another drawback is that stuff can be a mess to work with. It will ruin your clothes, and is difficult to remove from skin. Still, it would beat freezing to death.

Benjammin,
Another fine example of thinking outside the box!

Hmmm - what else can this "Great Stuff" be used for? Maybe blowing up the spare 1 gallon ziploc bag, coating the outside to improve the durability and rigidity of your improvised canteen.

Scott

The main problem with this stuff is that it comes out in "worms", rather than a spray. If you wanted to really coat the plastic, with minimal holes, you'll need several cans. I coated the inside of half a sphere (36" dia), and it took close to three cans.

And if you touch it (with anything), the foam collapses there, although it will puff up a bit before it skins over.

If you could make something like a latticework pattern with it, it would take less, IF it had enough strength to be useful.

The nozzles on Great Stuff tend to be more reliable (IME) than some of the less well-known brands.

What are the temperature limitations? How flammable is it? I would hate to have a warming fire outside the shelter and have the shelter go up in flames. Esp with me in it....

But if I had to carry 3 or 4 cans of foam, I might as well carry a decent tarp and not freeze to death while the wind was blowing the foam into my hair. <img src="/images/graemlins/smirk.gif" alt="" />

Sue

That sounds like a REALLY good idea, let us know how it turns out, but I think I'm gonna be picking up some cans BEFORE you try it, I can't see how it wouldn't help, even if it doesn't turn out as good as you might want it to... it just makes sense <img src="/images/graemlins/wink.gif" alt="" />

Troy

The product your talking about is using a straw application, but it can also be emitted as an airborne spray. The foamy worm stuff seems better suited to filling voids, whereas the spray is made for open surfaces (like roofs).

I can imagine applications for both, but I'll start with the spray on first for the shelter and then we can experiment from there.

I am hoping that once I build the shelter, spray it down, and let it cure out, the foam will be rigid and sturdy enough that I could uproot the little hut and take it with me to relocate.

Hmmm, that may not work so well, but I have some ideas on that too...

Why not just carry rain gear and spray the foam on that?

The ultimate solution for portable shelters! <img src="/images/graemlins/grin.gif" alt="" />

Yup, that'd work too. I was only thinking of the trash bag shelter because the usual failings of that application were spurring my creative process. This application could lend itself to several variations to be sure. One thing to be wary of is that whatever the substrate (garbage bag, mylar blanket or rain poncho), the application of the foam doesn't chemically react to melt the surface of what we'd be spraying it onto.

But can you imagine if you wore that rain gear sprayed with foam out in public? The only tune you'd be hearing is "They're Coming to Take Me Away, Ha, Ha"
<img src="/images/graemlins/grin.gif" alt="" />